Determination of low latitude plasma drift speeds from FUV images

Thousands of images of the nighttime equatorial airglow arcs have been obtained by the Far‐Ultraviolet Imager (FUV) on‐board the NASA IMAGE satellite. Imaging periods lasting several hours around the time of satellite apogee allow for the determination of the velocity of drifting plasma density depletions occurring within the airglow arcs. These velocities reflect the E × B drift of low‐latitude plasma under the influence of a vertical electric field. A survey of several weeks of data produces information regarding the variation of drift speeds with solar 10.7‐cm radio flux. Comparisons to previous measurements by the Jicamarca radar show that the FUV‐determined plasma drift speeds are 10–35% greater, particularly before 2100 local time. This difference is attributed mainly to the different magnetic latitudes of the observations.